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Perspectives

ReferenceInternational Business Law

Best practice for handling foreign law

The Hamburg Guidelines support German courts, experts, and parties in handling foreign law in international disputes – what they say and how to use them.

Peter Poleacov (updated )7 min

A desk globe against a blue sky, showing Africa and the Atlantic

Background

In a dispute, a German court also has to decide questions of foreign law to the extent foreign law applies. How the court determines foreign law is governed by Section 293 of the German Code of Civil Procedure (Zivilprozessordnung, ZPO). Under it, the court is not limited to the evidence the parties bring. It may also draw on other sources and order what is necessary to that end.

The court must determine foreign law of its own motion. Which routes it takes is in its sound discretion. Free-form evidence (Freibeweis) applies, so the court may use any means of evidence and any source of knowledge. The court’s options include commissioning an expert opinion on foreign law. The expert’s role, however, is limited to answering the court’s evidentiary questions about foreign law. The court itself always determines, interprets, and applies the private international law (PIL) in force in Germany. It also decides the specific case itself, that is, it finds the facts and applies the foreign law to them.

The expert opinion, however, should not be the standard route but the last resort. An expert opinion generally costs money and time. The Hamburg Guidelines therefore expressly recommend that the court commission one only where it cannot determine the relevant foreign law with sufficient certainty by simpler, faster, and less expensive means. According to the Guidelines, however, high costs alone do not make an expert opinion dispensable, even if they amount to a multiple of the amount in dispute.1 Under the BGH’s line, an expert opinion may be unnecessary where the sources are readily accessible and no contested questions of interpretation arise that would require in-depth engagement with foreign case law.2 If, as a party, you want to avoid an expert opinion, hand the court the simpler routes before it has to look for them itself. For you, that is the most important practical point.

Where the decision turns on foreign law, the court must discuss this with the parties (right to be heard). It must give them an opportunity to address how the foreign law is determined and what it says. Where the court has formed a preliminary view of the content of foreign law, for example based on its own research, it shares that view with the parties.3

The parties to the dispute may help the court determine foreign law. Beyond their general duty to promote the proceedings and to cooperate, however, they are generally not obliged to do so. Foreign legal rules are treated as rules of law, not as facts. The principles of burden of pleading and proof therefore do not apply to foreign law.4 For tactical reasons each party should nonetheless make submissions on foreign law. That alone makes it worth being represented in an international dispute by counsel who know the foreign law in depth themselves. If both parties, in proceedings over pecuniary claims, make detailed submissions on the foreign law that agree with each other, the court can usually accept them as correct, provided it has traced the sources and the submissions convince it.5 Where determining the foreign law proves disproportionately burdensome, it may, according to the Guidelines, be advisable for the parties to consider jointly choosing German law in the proceedings, to the extent the applicable PIL allows this.6

Under the BGH’s settled case law, the competent court must determine and apply foreign law in the way it is, or would be, applied by the courts of the respective country.7

How far the duty to determine foreign law reaches can be stated in general terms only to a limited extent. In 2025 the BGH again stressed that the circumstances of the individual case set the limits of the lower courts’ discretion. According to the BGH, the requirements rise the more complex or unfamiliar the applicable law is compared with domestic law.8 Simply consulting the sources is usually not enough, because what matters is how the courts of that country apply the law.7 In simple cases, according to the Hamburg Guidelines, the provisions themselves suffice where further information is hard to obtain and nothing suggests that practice departs from the statutory text.9

According to the Hamburg Guidelines, the requirements for determining foreign law in interim relief proceedings are in principle no lower than in main proceedings. The urgency may, however, mean that the foreign law cannot be determined.10 According to another view, a credible showing (Glaubhaftmachung) under Section 920(2) ZPO, that is, a summary review weighing the interests of both sides, suffices there instead of a full determination under the general principles of Section 293 ZPO.11

The application of foreign law itself is, according to the BGH, not reviewable on revision (referring to Section 560 ZPO in conjunction with Section 545 ZPO). The revision court is in principle bound by the findings of the court of appeal on the content of foreign law. The revision court reviews German law, but not foreign law. It does, however, review how the foreign law was determined, if only to a limited extent.12 It checks only whether the court of appeal exercised its discretion without error and made full use of the sources available to it.8

The Hamburg Guidelines

The Max Planck Institute for Comparative and International Private Law in Hamburg has published the “Hamburg Guidelines on the Determination and Application of Foreign Law in German Proceedings” (Hamburg Guidelines). They were developed in close exchange between practice and academia. The Guidelines support courts, experts, and parties (including their representatives) in handling foreign law in international disputes. They set out the relevant legal framework in compact form and offer a range of practical recommendations.13

The Hamburg Guidelines are primarily aimed at proceedings before civil courts. In principle, however, they also apply to other cases where German courts or authorities (for example, tax courts, criminal courts, asylum authorities, tax offices, civil registry offices) have to apply foreign law.14

The Hamburg Guidelines contain nothing on the international jurisdiction of German courts. Courts answer that question on their own, on the basis of the relevant legal sources such as the Brussels Ia Regulation (Regulation (EU) No 1215/2012).14

Conclusion

The Hamburg Guidelines are a useful instrument, but they do not change the basic problem. Foreign law before a German court costs time and money, and the outcome depends on how well the court understands an unfamiliar legal system. The Guidelines bring order to the process in which the court determines foreign law. They recommend commissioning the expensive expert opinion only as a last resort and show the parties ways to avoid it.

The real consequence, though, lies earlier, in the contract. A party that aligns governing law and jurisdiction never ends up in this situation. How differently the new Commercial Courts handle this is covered in the article “Commercial Courts in Germany”. In Saxony, for instance, jurisdiction is confined to disputes governed by German law.

The Hamburg Guidelines are licensed under the Creative Commons License CC-BY 4.0. Published by the Max Planck Institute for Comparative and International Private Law, Hamburg. Authors: Prof. Dr. Ralf Michaels and Priv.-Doz. Dr. Jan Peter Schmidt. The Hamburg Guidelines are available at doi.org/10.17617/2.3529891.

Notes

  1. Hamburg Guidelines (2023), Art. 2 § 3 No. 5; the first sentence is reproduced in Dostal, Die Ermittlung und Anwendung ausländischen Rechts gemäß § 293 ZPO im Licht der jüngsten Rechtsprechung des Bundesgerichtshofes, IWRZ 2025, 287. ↩

  2. BGH, order of 30 March 2021 – XI ZB 3/18: an expert opinion was unnecessary because no contested questions of interpretation arose that would have required in-depth engagement with English case law, and the sources were readily accessible. ↩

  3. Hamburg Guidelines (2023), Art. 2 § 2 No. 2. ↩

  4. Hamburg Guidelines (2023), Art. 1 § 1 No. 3; BGH, order of 24 August 2022 – XII ZB 268/19, referred to by the Guidelines. ↩

  5. Hamburg Guidelines (2023), Art. 2 § 2 No. 4. ↩

  6. Hamburg Guidelines (2023), Art. 4 No. 3. ↩

  7. See BGH, judgment of 5 July 2023 – IV ZR 375/21, para. 27. ↩1 2

  8. BGH, order of 20 February 2025 – I ZB 26/24. ↩1 2

  9. Hamburg Guidelines (2023), Art. 2 § 3 No. 4. ↩

  10. Hamburg Guidelines (2023), Art. 2 § 2 No. 3. ↩

  11. Dostal, IWRZ 2025, 287, on the reduced standard of review in proceedings under Sections 916 et seq. and 935 et seq. ZPO. ↩

  12. See BGH, judgment of 5 July 2023 – IV ZR 375/21, paras. 24, 26. ↩

  13. Michaels/Schmidt, Die Hamburger Leitlinien zur Ermittlung und Anwendung ausländischen Rechts in deutschen Verfahren, NJW 2024, 24, with further background, content overview, and outlook. ↩

  14. Hamburg Guidelines (2023), preliminary remarks. ↩1 2

Reference: Poleacov, P. (2026). Best practice for handling foreign law. INN.LAW. https://inn.law/en/perspectives/hamburg-guidelines/